Transparent gold as a platform for adsorbed protein spectroelectrochemistry: Investigation of cytochrome c and azurin

Idan Ashur, Olaf Schulz, Chelsea L. McIntosh, Iddo Pinkas, Robert Ros, Anne Katherine Jones

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The majority of protein spectroelectrochemical methods utilize a diffusing, chemical mediator to exchange electrons between the electrode and the protein. In such methods, electrochemical potential control is limited by mediator choice and its ability to interact with the protein of interest. We report an approach for unmediated, protein spectroelectrochemistry that overcomes this limitation by adsorbing protein directly to thiol self-assembled monolayer (SAM) modified, thin (10 nm), semitransparent gold. The viability of the method is demonstrated with two diverse and important redox proteins: cytochrome c and azurin. Fast, reversible electrochemical signals comparable to those previously reported for these proteins on ordinary disk gold electrodes were observed. Although the quantity of protein in a submonolayer adsorbed at an electrode is expected to be insufficient for detection of UV-vis absorption bands based on bulk extinction coefficients, excellent spectra were detected for each of the proteins in the adsorbed state. Furthermore, AFM imaging confirmed that only a single layer of protein was adsorbed to the electrode. We hypothesize that interaction of the relatively broad gold surface plasmon with the proteins' electronic transitions results in surface signal enhancement of the molecular transitions of between 8 and 112 times, allowing detection of the proteins at much lower than expected concentrations. Since many other proteins are known to interact with gold SAMs and the technical requirements for implementation of these experiments are simple, this approach is expected to be very generally applicable to exploring mechanisms of redox proteins and enzymes as well as development of sensors and other redox protein based applications.

Original languageEnglish
Pages (from-to)5861-5871
Number of pages11
JournalLangmuir
Volume28
Issue number13
DOIs
Publication statusPublished - Apr 3 2012

Fingerprint

Azurin
Spectroelectrochemistry
cytochromes
Cytochromes c
Gold
platforms
gold
proteins
Proteins
Electrodes
electrodes

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Transparent gold as a platform for adsorbed protein spectroelectrochemistry : Investigation of cytochrome c and azurin. / Ashur, Idan; Schulz, Olaf; McIntosh, Chelsea L.; Pinkas, Iddo; Ros, Robert; Jones, Anne Katherine.

In: Langmuir, Vol. 28, No. 13, 03.04.2012, p. 5861-5871.

Research output: Contribution to journalArticle

Ashur, Idan ; Schulz, Olaf ; McIntosh, Chelsea L. ; Pinkas, Iddo ; Ros, Robert ; Jones, Anne Katherine. / Transparent gold as a platform for adsorbed protein spectroelectrochemistry : Investigation of cytochrome c and azurin. In: Langmuir. 2012 ; Vol. 28, No. 13. pp. 5861-5871.
@article{b3024b51387e4768a37f51e4b00807b2,
title = "Transparent gold as a platform for adsorbed protein spectroelectrochemistry: Investigation of cytochrome c and azurin",
abstract = "The majority of protein spectroelectrochemical methods utilize a diffusing, chemical mediator to exchange electrons between the electrode and the protein. In such methods, electrochemical potential control is limited by mediator choice and its ability to interact with the protein of interest. We report an approach for unmediated, protein spectroelectrochemistry that overcomes this limitation by adsorbing protein directly to thiol self-assembled monolayer (SAM) modified, thin (10 nm), semitransparent gold. The viability of the method is demonstrated with two diverse and important redox proteins: cytochrome c and azurin. Fast, reversible electrochemical signals comparable to those previously reported for these proteins on ordinary disk gold electrodes were observed. Although the quantity of protein in a submonolayer adsorbed at an electrode is expected to be insufficient for detection of UV-vis absorption bands based on bulk extinction coefficients, excellent spectra were detected for each of the proteins in the adsorbed state. Furthermore, AFM imaging confirmed that only a single layer of protein was adsorbed to the electrode. We hypothesize that interaction of the relatively broad gold surface plasmon with the proteins' electronic transitions results in surface signal enhancement of the molecular transitions of between 8 and 112 times, allowing detection of the proteins at much lower than expected concentrations. Since many other proteins are known to interact with gold SAMs and the technical requirements for implementation of these experiments are simple, this approach is expected to be very generally applicable to exploring mechanisms of redox proteins and enzymes as well as development of sensors and other redox protein based applications.",
author = "Idan Ashur and Olaf Schulz and McIntosh, {Chelsea L.} and Iddo Pinkas and Robert Ros and Jones, {Anne Katherine}",
year = "2012",
month = "4",
day = "3",
doi = "10.1021/la300404r",
language = "English",
volume = "28",
pages = "5861--5871",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "13",

}

TY - JOUR

T1 - Transparent gold as a platform for adsorbed protein spectroelectrochemistry

T2 - Investigation of cytochrome c and azurin

AU - Ashur, Idan

AU - Schulz, Olaf

AU - McIntosh, Chelsea L.

AU - Pinkas, Iddo

AU - Ros, Robert

AU - Jones, Anne Katherine

PY - 2012/4/3

Y1 - 2012/4/3

N2 - The majority of protein spectroelectrochemical methods utilize a diffusing, chemical mediator to exchange electrons between the electrode and the protein. In such methods, electrochemical potential control is limited by mediator choice and its ability to interact with the protein of interest. We report an approach for unmediated, protein spectroelectrochemistry that overcomes this limitation by adsorbing protein directly to thiol self-assembled monolayer (SAM) modified, thin (10 nm), semitransparent gold. The viability of the method is demonstrated with two diverse and important redox proteins: cytochrome c and azurin. Fast, reversible electrochemical signals comparable to those previously reported for these proteins on ordinary disk gold electrodes were observed. Although the quantity of protein in a submonolayer adsorbed at an electrode is expected to be insufficient for detection of UV-vis absorption bands based on bulk extinction coefficients, excellent spectra were detected for each of the proteins in the adsorbed state. Furthermore, AFM imaging confirmed that only a single layer of protein was adsorbed to the electrode. We hypothesize that interaction of the relatively broad gold surface plasmon with the proteins' electronic transitions results in surface signal enhancement of the molecular transitions of between 8 and 112 times, allowing detection of the proteins at much lower than expected concentrations. Since many other proteins are known to interact with gold SAMs and the technical requirements for implementation of these experiments are simple, this approach is expected to be very generally applicable to exploring mechanisms of redox proteins and enzymes as well as development of sensors and other redox protein based applications.

AB - The majority of protein spectroelectrochemical methods utilize a diffusing, chemical mediator to exchange electrons between the electrode and the protein. In such methods, electrochemical potential control is limited by mediator choice and its ability to interact with the protein of interest. We report an approach for unmediated, protein spectroelectrochemistry that overcomes this limitation by adsorbing protein directly to thiol self-assembled monolayer (SAM) modified, thin (10 nm), semitransparent gold. The viability of the method is demonstrated with two diverse and important redox proteins: cytochrome c and azurin. Fast, reversible electrochemical signals comparable to those previously reported for these proteins on ordinary disk gold electrodes were observed. Although the quantity of protein in a submonolayer adsorbed at an electrode is expected to be insufficient for detection of UV-vis absorption bands based on bulk extinction coefficients, excellent spectra were detected for each of the proteins in the adsorbed state. Furthermore, AFM imaging confirmed that only a single layer of protein was adsorbed to the electrode. We hypothesize that interaction of the relatively broad gold surface plasmon with the proteins' electronic transitions results in surface signal enhancement of the molecular transitions of between 8 and 112 times, allowing detection of the proteins at much lower than expected concentrations. Since many other proteins are known to interact with gold SAMs and the technical requirements for implementation of these experiments are simple, this approach is expected to be very generally applicable to exploring mechanisms of redox proteins and enzymes as well as development of sensors and other redox protein based applications.

UR - http://www.scopus.com/inward/record.url?scp=84859447740&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84859447740&partnerID=8YFLogxK

U2 - 10.1021/la300404r

DO - 10.1021/la300404r

M3 - Article

C2 - 22369317

AN - SCOPUS:84859447740

VL - 28

SP - 5861

EP - 5871

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 13

ER -